Power Mac - need a answer quick help

I have a g4 digital audio tower with a dual 533mhz I need to know if i can do one of the 2 thing
1 if i bought a g4 with a dual 1.25ghz processor can i swap out the processor to my g4 digital audio? and do i need to reinstall anything like os x or final cut pro?
2 or can I take my hard drive from my with my os x and final cut pro and just put it in the other g4?